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Clock Key Size Chart Explanation
- 1.75mm = 000 Key
- 2.0mm = 00 Key
- 2.25mm = 0 Key
- 2.5mm = 1 Key
- 2.75mm = 2 Key
- 3.0mm = 3 Key
- 3.25mm = 4 Key
- 3.5mm = 5 Key
- 3.75mm = 6 Key
- 4.0mm = 7 Key
- 4.25mm = 8 Key
- 4.5mm = 9 Key
- 4.75mm = 10 Key
- 5.00mm = 11 Key
- 5.25mm = 12 Key
- 5.5mm = 13 Key
- 5.75mm = 14 Key
- 6.0mm = 15 Key
Clock keys have there own number system from 000 to 16 as seen in the Clock key size chart. However the number does not indicate what size is what number and can be confusing. So how do you use the Clock key size chart to get the right key?
It would make more sense if the key size was the MM of how wide the key was to fit, but this is not how it works. This section is to figure out what key number to order so the clock can be wound up. Subsequently, the clock key gets lost the most out of any other clock part.
Of course, it can be tricky to find the right key for your clock because there are many sizes. The Clock key size chart will give us the right size key to order.
Double End Clock Keys
In addition, some keys have two sizes on one key and this is called a double end key. By and large, the clock key size chart will work for both the wind up part of the clock and also the smaller F / S portion. When the clock has a F / S regulator portion it will be at the 12 o’clock on the dial.
Alternately, if there is a small arbor inside of a hole at 12, this is the time regulator control and the key would have two ends. Thus, it may say F / S at this location or A / R. F / S stands for Fast or Slow, or it could say A / R to stand for Advance or Retard and is referring to the timing of the clock.
Of course, if the clock is running fast in time, turn more to the Slow or Retard direction to slow it down. Refer to the Clock key size chart with your measurements to find a key to work with this function.
Getting the Right Clock Key Size
Given these points, to get the key needed, measure the shaft the key is to go on to, then use the Clock key size chart to get the key size needed.
Please do not call asking what key the clock needs, as you will be told it would still have to be measured. In short, measure the shaft that the key goes onto in MM and then use the clock key size chart to match it up.
The Lazy Way Instead of the Clock Key Size Chart
The Clock key size chart has all of the sizes listed however sometimes certain key sizes are known. Generally speaking, almost all post 1960 mechanical clocks, made in Germany take a size #8 key or crank, unless the movement is round.
Ordinarily the round ones take a number 4. The American time strike antique units mostly take the size 7 key. Match your measurements to the Clock key size chart to be sure.
I have an Ansonia Syria eight day strike clock. When I measure for key size I get 3.65. Which key would you say will fit it?
Thanks
Usually those are size 7
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I have Smiths clock the square on the winder measures 4mm across the flats do I need a 4mm key or a 4.25mm key to wind it.
I suppose the 4mm key, not sure. To be sure, what are the movement numbers off the back plate?
What are the numbers off of the back plate of the clock movement itself? If it is hard to get to, usually you can stick a cell phone up behind the movement and get a picture of the numbers. Or through the side access panel if there is one.
Not off the paper work, not off the wooden case, but the movement stamp itself
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I’m trying to operate a Stickley 89-85 Mantle clock but it had no key does anyone know what size key I need? Thank you.
What are the numbers off of the back plate of the clock movement itself? If it is hard to get to, usually you can stick a cell phone up behind the movement and get a picture of the numbers. Or through the side access panel if there is one.
Not off the paper work, not off the wooden case, but the movement stamp itself
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
The back of the clock says Franz Hemle and the numbers say 141-041 (later 38cm over 111 150 possibly) thank you.
Size 8 key from this link
https://www.clockworks.com/product/brass-single-end-clock-key
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Ok I was able to look inside the clock. It says Franz Hemle No (0) Jewels Unadjusted Made in Germany. 141-041 38cm then a number hard to make out under it maybe 111 and a symbol then 150 (it could be 1111150 but the middle looks more like an upside down small triangle. Additionally, I had a generic multi key sent but for whatever the right size might be the cylinder of the generic key is too big for the hole around the winding mechanism so I can’t use the multitool even though one might be the right size. Does this information give a clue as to what specific key I might buy to try to wind the clock? Thank you.
Takes a size 8 clock key
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Can I also clarify when I get a key do these wind in a counter clockwise fashion or clockwise? I never wound one before and don’t want to break it. Thank you
Depends on the clock. It will not break, just turn it whatever way it wants to go.
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Thank you for your response– I won’t be with the clock until the weekend but I will check it out as soon as I can.
Can someone advise me please as to what size key(s) my Gilbert clock would need?
It’s a 3 hole clock. I’m unable to post a photo.
Size 7 usually
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Hi – I have a french metal cased Jules Richard thermograph with a tall double graph clockwork drum – I estimate it is circa 1950-60’s. I am trying to find a key for it – the winding hole is around 6.5- 7″ below the top so needs a key shaft of that length – the squared drive looks to be around 3mm – but is difficult to tell with a torch !
Do you know where I could get a key to fit it
Seems size 3 or 4 is what is needed, this link
https://www.clockworks.com/product/brass-single-end-clock-key
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I was gifted a Gilbert 1807 mantel clock. it came without the keys. what size key should I purchase? thank you.
Size 7 usually, this link
https://www.clockworks.com/product/brass-single-end-clock-key
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I have a 1904 gilbert mantle clock, what size key would work? Is there anywhere that I can find new hands for it? Thank you for your information.
Usually size 7
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Thank you, James!
I have a key for a front wind mantel clock that is marked 4 OC. Do you know what size key this is?
Not sure on that one, size 7 or 8 usually
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Have Sligh mantle clock. Need a key for winding.
Size 8 usually
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I just purchased a Kern or Kuss iv no jewel dome clock which doesn’t have a key could you tell me what size it takes
Not sure on the size, need to measure it.
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
with gratitude
-catherine
Needs a size 8 key or crank for that one.
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Thank you so much! Just purchased 2 from Clockworks!!
I have a Elliot 8-day lever westminster chime clock from circa 1970 without key. Any idea of the size please
Size 8
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Hi have a an antique clock with a winding key marked “10” that says “Made in England” that works ok, but it’s very difficult to turn it because the weights are heavy, Do you know what size crank key I can replace it with? Thanks
From here, not sure. Size 10 maybe. You can lift the weights up with one hand and wind with the other so its not so much stress on the movement and yourself
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Grandmother left an antique New Haven 30 hour wall clock. It is missing the key and the pendulum. Do you know what size key and pendulum are needed?
Key size 7
https://www.clockworks.com/product/brass-single-end-clock-key
Suspension
https://www.clockworks.com/product/clock-pendulum-suspension-spring-rods
Adjustable bob =
https://www.clockworks.com/product/adjustable-mantle-clock-bob
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
What size adjustable bob?
Smallest or medium. Not the large.
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Bought a clock at a thrift store but it did not come with a winding key. Nameplate says “Beacon” made in Korea. Clock says “Regulator A” on the glass door. Any idea what key size I need for winding this clock?
Size 7 usually
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I am looking at buying an 1880’s Ansonia Royal Bonn porcelain 8 day clock. What size key do I need? Thank you very much.
Not sure on that one, usually size 7 though
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I just got a Bulova Tempus Fugit Mantel Clock that was my father’s, but with no key. I’m not sure what size it is. would anyone have any idea?
Size 8
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I just picked up a 1920’s Waterbury mantle clock at an auction but it has no key. The only key I have, which was to a 1980’s wall clock (long gone) is too large to wind the mechanism. I’m having difficulty in understanding what exactly one measures to determine the size key needed as only a small square sticks out of the front of the clock. It appears the same key would be used to wind the chime as well as the clock Any idea what size key I would need for this? thanks in advance for any advice you can offer.
Size 7
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
The key to my great grandmother’s Sessions 8 day mantle clock (c. 1920) was lost around 10 years ago, and I’d to get it going again. Any idea on what size key it takes?
Size 7 this link
https://www.clockworks.com/product/brass-single-end-clock-key
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I picked up a Bell Clock Co. 8-day bell strike mechanical clock recently, without a key. The two square winding shafts look to be 3/32″ across the flats, or a little less than 2.5 mm. Is a 1 key the proper one for this clock? Also, I don’t know when it was last serviced; it was not warranted to be in running condition. I have some instrument oil; are there any oiling points inside which might be user-serviceable?
Also, do you work on pocket watches? My grandfather’s railroad Hamilton 992 was serviced by a local watchmaker about ten years back, but the watch is no longer running and the watchmaker has gone out of business in the interim.
From here, not sure what size key. Do not work on the watches. Not much help I guess on this
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
New Haven Westminster Chime Mantle Clock. Need the two key model. What is the key info?
They used size 7 alot
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Just acquired a Howard Miller wall clock #648 wall clock. It came without a key. I have several clock keys but none fit and upon closer inspection, the shaft seems to have protrusions or extensions at the 4 corners. Is there a special clock key for this type of shaft or do I just need a larger key?
Usually size 8 key on that type of unit, this link
https://www.clockworks.com/product/brass-single-end-clock-key
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Dear James,
This is a wonderful article! I have a question about the Hermle 340-020 (post ’60s German) movement. Both copies that I own (1969 and 1978) have 4.0 mm shafts – should they use a #7 key as explained in the table, or you would you recommend the more common #8 key that probably fits a bit loose?
Sincerely,
Kevin
8 Fits best.
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Please do you happen to know what key size will be required for a Haller Foreign UR movement. 12cm 190,66.
3 winding holes. Its a Westminster 8 day mechanism. In a mantle clock.
Thank you.
Most likely size 8
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Would you be so kind as to confirm if the Junghan antique mantle clocks have a unique brass key, like the Chelsea clocks have?
Thank you kindly,
John.
Any key with the right size will work. Usually size 8 for that one
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Female here so I really didn’t understand all the stuff explained, I have a landshire mantle clock can anyone please tell me what size key thank you 👍
Female here, you can understand anything you make a decision to understand:)
Landshire loved electric clocks, are you sure there is no electric cord to plug in ? If not, what are the numbers off of the brass mechanism ?
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I have an English Bracket clock made by John Walker – London circa 1875-1900 that didn’t include the key. There is also a key required on the side that is used to open the front door, but it’s presently locked so I can’t open and measure the size of the shafts on the dial. Is the size of the side key the same as the winding key and what size is needed? Thanks
Do not have the door keys, this is more in the realm of the cabinet maker. My guess on the size of the clock key is size 8
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I just acquired a Landmark clock with Frank Hermle mechanism dated 1979. The square shaft width looks to be 3.5 to 4 mm. It’s difficult to get an accurate measurement. Any Ida of the key size?
Size 8 unless the movement is round, if round size 4
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I need a key for my Butler Grandmother clock
Door key or wind key?
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
a wind key
Size 8
https://www.clockworks.com/?post_type=product&s=Crank
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I need a key for Seth Thomas drop octagon strike wall clock model 1760-000. I have been told a size 7 key will work is that correct?
Yes usually
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Hello! My parents left their 1928-1932 Kienzle Westminster Chimes Mantel Clock for me as a gift. It needs a key and it needs to be repaired. My dad told me a while ago that the spring needed to be rewound, but I don’t know if that is correct. Can you help me with repairing it and finding a key for it? It was important to my parents so it’s important to me to get it fixed and running again.
Usually size 8 for that one
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I bought a size 6/4=3.6/1.8 MM was slightly to small, so what size do I need? I have a Sessions
mantal clock. I can’t find a date on it.
Usually size 7
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I have a clock movement that I got used. It is round and almost identical to a French exposed escapement movement from the 1800’s, but the escapement is not exposed. The time adjustment is a square pin above the 12 that is smaller than a 000 key. As close as I can measure it is 1.43 mm. I think the winding key is a 6, a 5 fits tightly.
Since I posted this I found there are 0000 and 00000 (4/0 and 5/0) out there. It looks like the 5/0 is what I need. See the chart at: https://antiquevintageclock.com/2017/08/31/clock-key-sizes-do-you-have-the-right-one/
I just received a Sankosha & Co. clock from Japan. Do not know era it is from. It is in a very ornate wood box 16″ by 8.3/4″ wide with glass door and chime. Any idea what key this would take? Thank you!
They liked size 7 alot
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I’m trying to verify the winding key size for a vintage Linden mantle clock from West Germany. I recently found this beautiful piece at our local Goodwill store and couldn’t leave it behind even though it was missing the key. By digging around online at other’s pictures that have the same clock, I think it could be a size 10. But, before I purchase one, I’d like to be sure on that. Any info you can share is greatly appreciated!! Thanks so much, Christine
I greatly appreciate that James!! I’ll be ordering the size 8. Have a good night!
Size 8 this link
https://www.clockworks.com/product/brass-single-end-clock-key
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Good People, Great website by the way. A great find. Question. I have a Maritime Seth Thomas clock and no key. Is a number four key proper? I ask because when you get to 3 mm its hard to measure without a caliber which I don’t have handy.
Usually size 3 for that one
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
Hello folks great site I have a German Herme mantlepiece clock from around 1967 on looking it’s about 4mm but only a guess would you know the key size to order please as it’s lost thanks
Hermle loved size 8 key for mantle units
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I have a Trend Clock (Zeeland, Michigan) from the 1950s; could be older. The clock number is 69308. When measuring the key shaft, I determined that it’s 3mm or 3.25mm (not totally sure). What is the correct key for this clock? And also, what direction do you turn the key to wind it?
Size 8 needed. It will only wind one way dont worry
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
What size key do I need for this little clock? It’s a tiny thing. Fits in your hand. Says W Germany on the back. The movement inside says “J ENGLSTLER MADE IN GERMANY NO (0) JEWEL UNADJUSTED”
Do not know on that one
James Stoudenmire
40yr Clockmaker
Author of Clockworks.com
I have a New Haven Clock Co, eight Galic(?) Day Cabinet. Any guess at key size. Or, how can I measure width when they are recessed? Thank you!
They liked size 7 alot, that is all I can say from here
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
Hello,
I have a Seth Thomas Adamantine Mantle clock, could you tell me what size winding key it takes? It is a c. 1900-1906 models with four exterior columns in white and green larger half columns against the main part of the clock.
It works great, but I know it’ll soon run out of wind.
Thank you,
Jason
Usually size 7
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
These keys do not fit winders on E. Ingraham clock
Thank you for your comments.
Usually size 7 for that one
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
Hi James – do you know what size key the “Blacksmith” New Haven Clock Co Mantle clock takes?
Thank you-
Should be size 7 for that clock
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
Thank you!
I have an e. Ingraham co. Bristol Conn. USA mantel clock, came with the two keys neither key fits the time or chime posts.
Should be size 7 for that clock
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
Attached is the clock from the previous message.
Usually size 7 for that one
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
I have a 1920s Seth Thomas Cymbal #1 mantle clock. I need a new key. Measuring the shafts is difficult because they are somewhat recessed. Just eyeballing it with my dial caliper, 3.5mm looks too big. 3.25mm looks about right. Thoughts?
Usually size 7 for that one
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
It actually took a number 5 – after some trial and error.
I have an English Smiths railway/school clock that’s approx 43cm overall in diameter with the actual face being approximately 30cm. We’ve just moved and I can’t for the life of me find the key!!! Argggh! So, desperate as I am to hear it ticking in our new home, I’m reaching out to you. Would you happen to know what key it might take?
Many thanks in anticipation,
Adrian
Guessing size 8, Best to measure
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
Great – thanks! Will give it a try!
I was gifted a Forestville 8 day mantel clock with chimes without the key. I took it to a local jewelry store who ordered some keys but none fit. How do I find the right key.?
Usually size 7 for that one
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
thank you! I’ll let you know.
What size key do I need? I have a Howard Miller, New Haven Wall, 620-196 with a Kieninger Clock Movement SPS-02 with Wesminster Chime – it has three key holes in the front of the clock face.Description of the movement is:
Kieninger Clock Movement SPS-02 is a 1/4 key wind movement with Westminster chime, run time 8 days, plate size 120 x 124 x 1,7 mm, spring driven, on 12-rod gong, pendulum version with Kieniramic7 solid anchor with stationary escapement (Graham) and automatic beat adjustment, cable/key wind movements with cable winding stops, chime shut-off, front winding.
Size 8 this link
https://www.clockworks.com/product/brass-single-end-clock-key
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
Thank you so much! Have a great day!
Curious? Tera, is your last name Helser or Heiser? The name caught my eye – I am not aware of many of us Helsers. Sorry, not clock related. Initially looking for a clock key.
I have a 1970’s Howard Miller Jennison wall clock which says no 143 Triple chime key wind movement, model 612-432. Can you please tell me the ket size I need? It has been lost.
Size 8 for that one, this link
https://www.clockworks.com/product/brass-single-end-clock-key
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
Thank you so much!